The invention relates to a device for adjusting the ignition time of an internal combustion engine for a motor vehicle in order to minimize a volume of poisonous exhaust gas from the engine.
In the idling and low speed modes of operation, internal combustion engines for motor vehicles produce poisonous exhaust gases in large volumes. In order to minimize the volume of poisonous exhaust gas from such engines, it has been already practiced to adjust the ignition time of the engines in accordance with the mode of operation thereof. For example, a plurality of relays have be provided one for each of mode sensors for sensing the respective modes of operation of the engine and selectively energized in accordance with the outputs from the associated mode sensors to adjust the ignition time of the engine. Alternatively, the outputs from such mode sensors could be processed by a logic circuitry to control a single relay for adjusting the ignition time of the engine. With the sensors each formed of a semiconductor circuit or with the outputs from the sensors processed by a semiconductor logic circuitry, the resulting adjusting device has been often disposed within a compartment of the associated motor vehicle. This is because the device disposed within an engine space maintained at an elevated temperature of the vehicle causes a decrease in reliability of the same. In that event, if a control element involved is formed of a relay or relays then a problem has arisen as to noise generated upon closing and opening electric contacts included in the relay or relays. In order to avoid this problem, only the relay or relays might be disposed in the engine space. This, however, has resulted in the complicated wiring around the relay or relays and also in a decrease in the system reliability as well as very inconvenience in practice use.